Electrically conducting polymers have developed into a material of choice for a variety of organic optoelectronics applications. Such applications for optoelectronics include polymeric light emitting diodes (thin film displays), solid state lighting, organic photovoltaics, advanced memory devices, organic field effect transistors, ultracapacitors and electroluminescent devices.
One of the first of many electrically conducting polymers was polyacetylene and the discovery of conductivity in such polymer created substantial interest in other types of electrically conducting polymers. Recently, conjugated poly(thiophenes) and substituted thiophene derivatives have been discovered to have electrically conducting properties. A feature of these polymers is that they can be cast into films and doped with conventional p- and n-type dopants or the doped polymers can be cast into films and their electrical properties modified accordingly, thereby lending themselves suitable for use in a variety of optoelectronic applications.
Representative articles and patents illustrating thiophene monomers and electrically conducting polymers including thiophene and derivatives thereof are as follows:
U.S. Pat. No. 6,645,401 discloses conjugated polymers of dithienothiophene (DTT) with vinylene or acetylene connecting groups as suitable for producing semiconductors or charge transport materials useful in electrooptical and electronic devices including field effect transistors, photovoltaic, and sensor devices. Polymers containing DTT formed by electrochemical polymerization were known but had limitations in terms of solubility and photovoltaic properties.
U.S. Pat. No. 6,585,914 discloses fluorocarbon-functionalized and/or heterocyclic modified poly(thiophenes) such as α,ω-diperfluorohexylsexithiophene for use in forming films which behave as n-type semiconductor. These poly(thiophenes) also can be used to form thin film transistors with FET (Field effect transistor) mobility.
U.S. Pat. No. 6,676,857 discloses polymers having polymerized units of 3-substituted-4-fluorothiophene as liquid crystal materials for use in semiconductors, charge transport materials, electrooptical field effect transistors photovoltaic and sensor devices.
U.S. Pat. No. 6,695,978 discloses polymers of benzo[b]thiophene and bisbenzo[b]thiophene and their use as semiconductors and as charge transport materials in electrooptical devices.
U.S. Pat. No. 6,709,808 discloses image forming materials incorporating electrically conductive polymers based upon pyrrole-containing thiophene polymers and aniline containing polymers.
US2004/00010115A1 discloses homopolymers and copolymers comprised of repeating units of thieno[3,4-b]thiophene for use in electroactive applications. Copolymers can be formed with 3,4-ethylendioxythiophene, dithiophene, pyrrole, benzothiophene monomers, and the like.
The article, Synthesis and Electronic Properties of Poly(2-phenyl-thieno[3,4-b]thiophene): A new Low Band Gap Polymer, Chem. Mater. 1999, 11, 1957–1958 discloses various thienothiophene polymers including poly(2-phenyl thieno[3,4-b]thiophene) and poly(2-decyl thieno[3,4-b]-thiophene) as conducting polymers.
The article, Poly(2-decyl thieno[3,4-b]thiophene): a New Soluble Low-Band gap Conducting Polymer, Synthetic Metals 84 (1997) 243–244 discloses various polymeric thienothiophenes including poly(2-decyl thieno[3,4-b]thiophene) and a process for preparing the polymer.